In general, conventional vertebral locking and retrieving systems of the prior art involve a locking process of multiple vertebrae, as exemplified by rods sold under the trademarks LUGUE and HARRINGTON, both made by Zimmer Company of U.S.A., and plates sold under the trademark ROYCAMMILE produced by Howmedia Corporation of U.S.A. Such known prior art arrangements require a surgeon to make a long incision, which generally takes up too much of a surgeon's time and may bring about an excessive bleeding by a patient receiving the treatment. The case in point is the LUGUE rod, which must be secured to two upper and lower vertebrae immediately adjacent to the injured or the deformed vertebra. This means that a surgeon is required to make a large incision to fix at least five segments of the spinal column. As a result, the patient's ability to move about is greatly hampered in the wake of such a surgical operation. In addition, the pressure exerting on the patient's nervous system by the locking and retrieving system of the prior art can not be effectively mitigated in view of the facts that the locking process is confined to a rear plate and that the retrieval of a front plate is not possible.
The prior art device for use in correcting the lateral curvature of the spine, such as the CD scoliosis correcting device made by Sofamor Company of France, is defective in design in that its lateral correcting effect is so limited as to result in an unequal intervertebral distance on both sides of the vertebrae. In addition,, the prior art device mentioned above has a serious drawback that it is unable to provide a simple and effective locking mechanism either in the longitudinal direction or in the horizontal direction.
With a view to overcoming the drawbacks of the above-mentioned systems and approaches of the prior art, one of the present inventors, Chih-I Lin, discloses an improved vertebral locking and retrieving system in U.S. Pat. No. 5,176,679. However, such a system is not suitable for use in the surgical treatment of scoliosis, especially osteoporotic degenerative scoliosis.